Multiplexing circuits are well known in the art. The most common multiplexing circuits comprise resistors and switches operably coupled together for selectively switching an input to a plurality of outputs, as illustrated in the prior art multiplexing circuit 100 of FIG. 3. In FIG. 3 the number of resistors 110 required on the input 120 equals the number of selectable outputs 130. The switches 140 are controlled for selectively coupling the input 120 to the outputs 130. The operational amplifiers 150 are biased by reference voltages 160 and have a resistor 170 in a feedback path so that they operate as current-to-voltage converters. The input resistors 110 are arranged in parallel and as a consequence the overall input impedance reduces by increasing the number of outputs 130. Multiplexing circuits drive other circuits, and therefore need to have relatively high input impedance as will be appreciated by those skilled in the art. One method of maintaining the input impedance of the multiplexing circuit of FIG. 3 after increasing the number of selectable outputs is to increase the resistance value of the input resistors. However, increasing the resistance value of the input resistors requires larger resistors which occupy larger die area on an integrated circuit.